The politically connected group that opposes the controversial Prospect Park West bike lane is poised to sue the city — at the risk of a marital rift between cycling advocate Sen. Charles Schumer and his lane-hating wife.

Neighbors for Better Bike Lanes — which includes Schumer’s wife, the former Transportation Commissioner Iris Weinshall, and former Sanitation Commissioner Norman Steisel — says it “plans to file suit” over a cycle path that it says was installed based on incorrect information by an agency that intentionally ignored the facts.

And here’s where the plot thickens: The group’s pro-bono attorney is none other than Schumer campaign contributor Jim Walden, whose name was tossed around in 2009 as a possible U.S. Attorney, though the job ultimately went to another Schumer ally.

Opponents claim that the bike lane was originally proposed as a one-way lane, and that the two-way version that ended up being built last year it is dangerous for pedestrians. Foes want the lane to be reconfigured or moved into Prospect Park.

“Our requests have been ignored,” said group member Louise Hainline, who is also a dean at Brooklyn College. “No alternatives have been broached at public meetings.”

But as the group calls into question lane safety, cyclists call into question the integrity of a well-connected group that represents the lane-hating minority in Park Slope.

“It’s a small group of wealthy and powerful people who don’t like it,” said Eric McClure, of Park Slope Neighbors, which supports the bike lane. “It’s really a shame; it would appear they are trying to play on political connections.”

That accusation is partly directed at Walden, who last year contributed $4,800 to Schumer’s campaign.

Last year, a survey by the neighborhood’s two councilmen found that only 22 percent of residents want Prospect Park West to be restored to its original, bike-lane-free state.

Despite the opposition and threat of a lawsuit, the Department of Transportation has trumpeted the lane. Earlier this year, agency data showed that the lane has made the area safer. Fewer drivers now treat Prospect Park West like a speedway, fewer bicyclists are using the sidewalk, and fewer cyclists are getting into accidents.

Weinshall and Steisel did not return calls seeking comment, and a spokesman for Schumer would not comment on his affiliation with attorney Walden or whether he supports the bike lane.

In 2005, however, the Senator told the New York Post that he and his wife share opposing views on cyclists.

“The bike people drive her crazy,” he said. “But they know they have an ally in me.”